Zappe has his limitations but I’m not sure there’s much of a physical/athletic gap between him and Jones. Best as I can tell, Zappe is functionally better with his feet, moves better, quicker, stronger core/trunk. The only meaningful difference between the two of them appears to be 2” of height, which isn’t nothing, but I don’t think it’s the end-all-be-all (or even that big of a deal).
And putting aside direct comparisons, a 6’1” QB - while not ideal if you were crafting a perfect player in a lab - is plenty of height to play, start, and thrive as an NFL QB, so long as other parts of their game are played at a high-level. Brees, Wilson are ample proof, and they’re both shorter than Zappe.