jC/jD vs. jA/jB

We all know all the blabbery about Mary's jump D is godly, except vs. Benis own jD, and Lin's, Seth's etc. but..

Can we conclude that weak (jumping or standing) attacks will always beat strong jumping attacks?

Like Im using Chang and his close/jumpin A can smash most jumping attacks. Ditto with Takuma's far B and Mary's far and DwnFwd Bs, among others (Clark's jA, King's jB, etc...)

Can't conclude that. The placement, speed, and timing of the jumping attack is what matters. For example, King's jump B is fairly good if you use it as a hop to defeat jumpers. If you try to use King's jump B to counter someone who is hopping themselves it normally won't work.

However your conclusion may have some credit... jumping light attacks are typically faster than jumping heavy attacks. This gives them a chance to come out before most heavy attacks.

Mary's jump D can be defeated. Mary jumps too low. I've beaten that thing with Iori's hyper jump C. Iori jumps higher than Mary and his C hits downwards. Mary's jump D also hits downwards. Because of that Iori's C will beat her jump D due to the fact that Iori simply can jump higher.

You know what jumping normal cannot be beaten? Clark's jump D. In an air to air battle in which both Clark and somene else does a normal at the same time, Clark almost always wins. The only reason Clark would lose is if he went against someone with a godly air-to-air jumping attack (like Takuma's CD) and ended up doing his attack an inopportune time.