“As he showed them real hands and a real side, he really ate with his disciples; really walked with Cleophas; conversed with men with a real tongue; really reclined at supper; with real hands took bread, blessed and broke it, and was offering it to them. ..Do not put the power of the Lord on the level with the tricks of magicians, so that he may appear to have been what he was not, and may be thought to have eaten without teeth, walked without feet, broken bread without hands, spoken without a tongue, and showed a side which had no ribs.” (St Jerome, from a letter to Pammachius against John of Jerusalem 34, 5th century)
In a few weeks, they went from a broken group of disappointed men and women, hiding behind locked doors in an upper room, to fervent evangelists, ready to proclaim their faith out loud in the synagogue and the marketplace, and to die for it if they needed to do so.
To me, this seems strong evidence that they believed they had witnessed everything that Jerome talks about above. Their belief in the resurrection makes sense of the survival of Christianity past its early start as a persecuted minority favoured by the lowest classes. Does this ‘prove’ the resurrection? No, of course not. You are free to believe with the disciples or not to believe. Does it explain the reason for the resurrection? No, again. For that, we look to the Church, and 2000 years of meditation from devout, thoughtful, and intelligent men and women.