The prophecy stated that someone born at the end of July, 16 years before the events of Harry Potter and the Half Blood Prince ,had a power he did not, and could destroy him; Voldemort concluded it was Harry, who was born on July 31st of that year.
What the prophecy referred to basically meant that it could be either neville or harry who ends up defeating him. so voldemort thought it was harry, which is why he went to kill him as a baby that night. the prophecy never stated which of the boys it would be so it was voldemort who made the chosen one to be harry, by getting to him first. if voldemort had ended up choosing neville first instead of harry, neville would’ve ended up being the chosen one. so yes he would’ve defeated him
