That implies the Engineers gave humanity modern wheat despite all evidence to the contrary. Or took our modern wheat back to their abandoned and dead planet despite all movie evidence to the contrary.
It’s just a stupid plot point in a movie full of them, but it did have xenomorphs murdering the dumbest scientists in existence so it’s not all bad.
Of course, this is also the series that had the engineers “life seed” Earth with literally just a dude breaking down into DNA. Because why shouldn’t an incredibly advanced alien species splooge into a river 4 billion years ago then just let it cook until it’s time to abduct and train Jesus?