"I have noticed from various sources that Easter is pre-Christian in origin. I had assumed that it is a Christian commemoration of the resurrection of Christ and dating from the original Apostles. What is the answer?" A common assumption is that Easter was instituted by the Apostles to commemorate the resurrection. But read, for a moment, what church leaders and secular historians - both ancient and modern - say:
Miss E. W.,
The Catholic Encyclopaedia gives this information under its article "Easter": "The English term [Easter]... relates to Eostre, a teutonic goddess of the rising light of day and spring..."
About Easter eggs, this same article states that the "custom may have its origin in paganism, for a great many pagan customs, celebrating the return of spring, gravitated to Easter."
The Encyclopaedia Britannica mentions "There is no indication of the observance of the Easter festival in the New Testament, or in the writings of the apostolic Fathers" (article "Easter" in the Eleventh Edition). The article mentions further that the church historian Socrates "attributes the observance of Easter by the church to the perpetuation of an old usage, 'just as many other customs have been established.'" "This [concludes the Britannica] is doubtless the true statement of the case. The first Christians continued to observe the Jewish festivals, though in a new spirit."
Sir James Frazer in his eleven-volume work The Golden Bough says this: "Now the Easter rites... bear in some aspects a striking resemblance to the rites of Adonis [a Greek god], and I have suggested that the Church may have consciously adapted the new festival to its heathen predecessor for the sake of winning souls to Christ" (Vol. V, page 306).
The church historian Eusebius states that Polycarp - a disciple of the apostle John - maintained that New Testament practices should be observed instead of incorporating heathen customs into the Christian liturgy. He even journeyed to Rome to try to convince the bishop Anicetus about this matter.
Half a century later - about 190 A.D. - the Roman bishop Victor attempted to excommunicate the entirety of the Eastern Churches for continuing to observe the New Testament paschal commemoration of Christ's death. It was three centuries before Easter generally supplanted the New Testament practice, and introduced the idea of a sunrise resurrection holiday. The English historian Bede tells us the New Testament observance continued in Scotland up to the seventh century.
The sources you noticed are right. Easter customs are of pre-Christian origin.
The full story about the origin of Easter is available in a booklet on the subject. It is sent free of charge upon request as a public service.