From the Encyclopedia Britannica: https://www.britannica.com/topic/Easter-holiday
Easter, Latin Pascha, Greek Pascha, principal festival of the Christian church, which celebrates the Resurrection of Jesus Christ on the third day after his Crucifixion. The earliest recorded observance of an Easter celebration comes from the 2nd century, though the commemoration of Jesus’ Resurrection probably occurred earlier.
The English word Easter, which parallels the German word Ostern, is of uncertain origin. One view, expounded by the Venerable Bede in the 8th century, was that it derived from Eostre, or Eostrae, the Anglo-Saxon goddess of spring and fertility. This view presumes—as does the view associating the origin of Christmas on December 25 with pagan celebrations of the winter solstice—that Christians appropriated pagan names and holidays for their highest festivals. Given the determination with which Christians combated all forms of paganism (the belief in multiple deities), this appears a rather dubious presumption. There is now widespread consensus that the word derives from the Christian designation of Easter week as in albis, a Latin phrase that was understood as the plural of alba (“dawn”) and became eostarum in Old High German, the precursor of the modern German and English term. The Latin and Greek Pascha (“Passover”) provides the root for Pâques, the French word for Easter.
The date of Easter and its controversies
Fixing the date on which the Resurrection of Jesus was to be observed and celebrated triggered a major controversy in early Christianity in which an Eastern and a Western position can be distinguished. The dispute, known as the Paschal controversies, was not definitively resolved until the 8th century. In Asia Minor, Christians observed the day of the Crucifixion on the same day that Jews celebrated the Passover offering—that is, on the 14th day of the first full moon of spring, 14 Nisan (see Jewish calendar). The Resurrection, then, was observed two days later, on 16 Nisan, regardless of the day of the week. In the West the Resurrection of Jesus was celebrated on the first day of the week, Sunday, when Jesus had risen from the dead. Consequently, Easter was always celebrated on the first Sunday after the 14th day of the month of Nisan. Increasingly, the churches opted for the Sunday celebration, and the Quartodecimans (“14th day” proponents) remained a minority. The Council of Nicaea in 325 decreed that Easter should be observed on the first Sunday following the first full moon after the spring equinox (March 21). Easter, therefore, can fall on any Sunday between March 22 and April 25.
Eastern Orthodox churches use a slightly different calculation based on the Julian rather than the Gregorian calendar (which is 13 days ahead of the former), with the result that the Orthodox Easter celebration usually occurs later than that celebrated by Protestants and Roman Catholics. Moreover, the Orthodox tradition prohibits Easter from being celebrated before or at the same time as Passover.
Easter has its roots in the Jewish Passover. Jesus was put to death at the time of the Jewish Passover and raised again on the first day of the week which is Sunday. Hence, Easter Sunday is an annual commemoration of the resurrection of Jesus Christ from the dead to eternal life. Its celebration was disconnected timewise from the Jewish Calendar in the time of Constantine, so it is actually out of sync with the Jewish Passover.
There is no commandment given in the New Testament to observe Easter Sunday, it is a ‘tradition of men’.
Only one observation is commanded in the New Testament and that is for baptised believers to meet often to share bread and wine in remembrance of Christ’s sacrifice.
At what is known as the ‘last supper’ Luke records:
Luke 22:15 And he (Jesus) said unto them, With desire I have desired to eat this passover with you before I suffer: 16 For I say unto you, I will not any more eat thereof, until it be fulfilled in the kingdom of God. 17 And he took the cup, and gave thanks, and said, Take this, and divide it among yourselves: 18 For I say unto you, I will not drink of the fruit of the vine, until the kingdom of God shall come. 19 And he took bread, and gave thanks, and brake it, and gave unto them, saying, This is my body which is given for you: this do in remembrance of me. 20 Likewise also the cup after supper, saying, This cup is the new testament in my blood, which is shed for you.
1 Corinthians 11:23 For I have received of the Lord that which also I delivered unto you, That the Lord Jesus the same night in which he was betrayed took bread: 24 And when he had given thanks, he brake it, and said, Take, eat: this is my body, which is broken for you: this do in remembrance of me. 25 After the same manner also he took the cup, when he had supped, saying, This cup is the new testament in my blood: this do ye, as oft as ye drink it, in remembrance of me. 26 For as often as ye eat this bread, and drink this cup, ye do shew the Lord’s death till he come.
Believers should use the opportunity to examine themselves
1 Corinthians 11:27 Wherefore whosoever shall eat this bread, and drink this cup of the Lord, unworthily, shall be guilty of the body and blood of the Lord. 28 But let a man examine himself, and so let him eat of that bread, and drink of that cup. 29 For he that eateth and drinketh unworthily, eateth and drinketh damnation (condemnation) to himself, not discerning the Lord’s body.
The early Church found it convenient to meet on the first day of each week and this became a tradition.
Acts 20:7 And upon the first day of the week, when the disciples came together to break bread, Paul preached unto them, ready to depart on the morrow; and continued his speech until midnight.
1 Corinthians 16:2 Upon the first day of the week let every one of you lay by him in store, as God hath prospered him, that there be no gatherings when I come.
In conclusion, the Christian celebration of Easter (like Christmas) owes more to pagan observations than to scripture.
I hope you find this helpful.