If Jesus did not actually resurrect, then he/she/they (the apostles etc.) soon would have visually seen his remaining corpse.1 This is relevant because they did not see a remaining corpse of Jesus's, but they continued believing Jesus resurrected.
For Jews like the Apostles (and others), mere ostensible visits from a dead person would not be interpreted as a resurrection appearance or suggest that a resurrection had occurred. (After all, a resurrection is a very particular thing in Jewish thought, and other categories of interpretation would much sooner present themselves[Forthcoming]. Something convinced them that this was not a ghost, hallucination, etc.)1.