Maybe this?
Well, we all know that, on that one night when james and lily died,
lily was with harry, and james defended the door
ergo- james died first, then lily.
In GoF when the spirits of those voldemort had killed were coming from his wand, james came out before lily, meaning he died after her.
theres a few things i think about this.
maybe james survived the first aveda, like harry did, maybe its justa potter thing, making it possible for neville to be voldys bane.
why would it be a potter thing...well rumours are that harry is a decendant of slytherin, or gryffindor
being a decendant of one of these would prove a 'reasonable' sxplanation.
or maybe harry uses a timeturner, in his seventh year
being old enough, and being the double of his father, maybe witnesses saw harry at the door, harry dies, lily is killed, james discovers them and is killed.
therefore leading to a good reason for harry to die,
it also means voldemort eventually wins