Pikeman may have a higher damage per shot, but given the higher propensity for headshots due to higher accuracy and higher rate of fire, Wardens actually have higher DPS depending on the Nord. The accuracy you are citing only occurs with the very best weapons in the game and is not indicative of innate class imbalance. However, this argument is entirely based on Nord HP threshholds. As you stated, some of the stronger Nords like Valkyries die in one headshot instead of two for Master Peltasts. This is only because the damage you are putting out just so happens to barely pass over the threshhold for the spears and is just barely under for the bow, and I would again argue that this only occurs with the very best items.
The game handles speed differently between weapon types. Having the same value for rate of fire between bows and throwing does not mean they fire at an equal rate. The Heavy War Hammer has a speed of 82, is it also just as fast?
Weight is debated above.
Lower athletics is factually correct.
More melee ability (and less armor value) makes sense given that Warden is, as you said, the "100% ranged Hero"
Jump throwing isn't particularly accurate and usually has very low damage output because of it. Its strategic significance is minimal.
I'm not quite sure what jiggle peaking is, but I'm guessing it is when you pre-cock your arm to throw before peaking. Wardens can do this to a small extent by beginning the draw before peaking, but you are correct that Master Peltasts do it better. However, one could argue that Wardens have higher accuracy (again, other than at the top of the weapon chain) and that more than makes up for it in the world of peaking.
Piercing shields can be useful, but it does significantly reduced damage to the point where, due to threshholds, many Nords will still take the same number of hits to kill after the shield is broken (1 or 2 lol). In this case, you could spend an extra four spears breaking a shield before doing the normal two hits to kill him. With Warden, however, you could have already done two headshots and be on to the next one. I would greatly prefer killing Juggernauts, Followers of X, and Queensguard with a bow than with throwing spears, as the accuracy (and projectile speed, something that has yet to be mentioned but makes a massive difference on overall accuracy) makes popping their heads much easier and quicker than trying to brute force your way through shields.
The increased speed of using medic boxes and other deployables is one small advantage Master Peltasts hold over other classes.
I am not sure that as a whole these differences make Master Peltast better than Warden. I'm also not sure if you are arguing for team based play, kiting, or in general. It also isn't clear if you mean in general or only at the highest level of play, as you only cite the rarest, strongest weapons. However, most importantly, you have yet to cite one thing you specifically want fixed in conjunction with a proper way to fix it. The athletics could be argued The two suggestions that were made were both shown to not be effective (increasing damage on Typhoon and Zephyr only helps the 3ish people that have them, adding a power draw to Warden won't actually increase damage as they have already crossed the Power Draw/Difficulty threshhold). It is hard to argue about subjective things like "which class is better" and time would be better spent on arguing numbers, problems, and solutions.