You’ve probably yourself wondered why eggs, rabbits are symbols of Easter and the origin of Easter itself. Long before the Christianization of European tradition and other cultures there was celebration for the rite of spring. Before Christianity (Ēostre or Ostara Old English: Ēastre, Old High German: Ôstara, and Austrō in Proto-Germanic language) itself derives from prefix of the Proto-Indo-European root *aus-, meaning ‘to shine’. Linguists have also connected this name to one of the most important goddesses of reconstructed Proto-Indo-European religion. She is the personification of dawn named Hausōs in reconstructed Proto Indo-European.
The first reference to such a goddess is attributed to Eostre is written by a Christian Monk by the name of Bede in Monkwearmouth, Northumbria, England. His book The Reckoning of Time (De temporum ratione) (725) when discussing the English months.
“Nor is it irrelevant if we take the time to translate the names of the other months. … Hrethmonath is named for their goddess Hretha, to whom they sacrificed at this time. Eosturmonath has a name which is now translated “Paschal month”, and which was once called after a goddess of theirs named Eostre, in whose honour feasts were celebrated in that month. Now they designate that Paschal season by her name, calling the joys of the new rite by the time-honoured name of the old observance. Thrimilchi was so called because in that month the cattle were milked three times a day…” (Bede .53-54)
So it can be inferred that she is a literal personification of the first light from the rising of the sun in the spring equinox, consequently light, and fertility. The month of April or Ōstar-mānod (Ostermonat, Easter month) on the Germanic Calendar; the goddess the very namesake of the month. Of course this conclusion is not exempt from some conjecture. Whether or not she was indeed simply a fertility goddess, or rather a goddess of sunrise. I think it’s abundantly clear that she is the latter, as even her name is the akin the direction of dawn. It’s then unavoidable to be associated with the sun, growth, fertility.
The connection for rabbits to the old tradition is also often contested by scholars on the subject. Charles J. Billison in Folk Lore Vol.III (1892) cites that there are many references to folk customs in Northern Europe during this period involving hares…
“whether there ever was a goddess named Eostre, or not, and whatever connection the hare may have had with the ritual of Saxon or British worship, there are good grounds for believing that the sacredness of this animal reaches back into an age still more remote, when it probably played a very important part at the great Spring Festival of the prehistoric inhabitants of this island. It appears likely that the hare was originally a totem, or divine animal among the local aborigines, and that the customs at Leicester and Hallaton are relics of the religious procession and annual sacrifice of the god.” ( Billison. 448)
Rabbits as well have always been a strong symbol of fertility, and fecundity. Prolific for their reproductive ability, even being able to conceive one litter of offspring while still being pregnant with the first. Eggs of course are laid by birds in the spring, and the Easter Rabbit or Easter Hare goes about in a literal way giving new life and birth, in a symbolic representation of the goddess. German immigrants brought the Easter Hare to Sweden in the late 19th century, However, due to a misunderstanding of the Swedish word for the Easter Hare, Påskharen, which sounds very similar to Påskkarlen, meaning the Easter Man or the Easter Wizard, the Swedish tradition of the Easter Wizard. The Easter Wizard was seen a suitable symbol for the pagan Easter traditions of Sweden (which I think is pretty neat) where still today children dress up as witches at Easter.
Whether or not it’s clear that there ever was a goddess in Europe dedicated alone to the celebration of the spring Equinox. Tacitus described in Germania or (De Origine et situ Germanorum) (98) that the early Germanic peoples only celebrated three seasons equivalent to spring, summer, and winter. Although much of what the Romans wrote about the Germanic peoples is considered with prudence. Íslendingabók or (The Law Book of Iceland) states Germanic Icelanders divided the year into only summer and winter. (I believe this could however be related to the geographic conditions of Iceland itself.)
Whether this was an actual deity goddess that was worshiped by early Germanic peoples is under a lot of conjecture; very littler is written in reference to her. As well much of what is written could have been done so to create an image of the pagan Europeans from the perspective of Christians. So rather than give definitive answers; instead you can yourself look on it critically as I myself do, and I encourage you draw your own conclusions on the subject.