From most like to least likely, according to academics, the hypotheses are:

1. Literary device (mythical fiction)
2. Impostor (Someone else pretending)
3. Visions and grievance hallucinations (these happen)
4. Only mostly dead (was not quite killed)

By far, the consensus is literary device, and there are even indications of stages, starting with the empty tomb and embellished by later authors.

No explanation needed. What is asserted without evidence can be dismissed without evidence.

Being around for free drinks is pretty on brand for actual Jesus, too.