Your stance is confusing me though, are you implying that before barbells, humans had no other methods for getting strong or lifting heavy things off the ground? You're on a primal message board, so the idea of picking up rocks, carcasses, etc shouldn't be foreign to you. Nowadays we have other fun things to pick up, and not all are conveniently equipped with a handy metal bar for easy pick up. If you truly cared about the best methods to "pick heavy things up" you would be training with sandbags or something similar. Few things in nature resemble a barbell... or none, so if you needed to pick up a person, training that movement with a sandbag would prove more beneficial than with a barbell.
Maybe we need to back up and you can explain what you meant when you asked me the original question, which was "What are the non-barbell ways to progressively train yourself to lift very heavy things off the ground?" .. and to which I replied with some serious responses, like sandbags, and some jokes, like family members. The way you phrased the question makes me think you think ONLY barbells are a way to get strong, which is frankly ridiculous as has been proven for hundreds of years before the "iron game" was even thought of.
I'm not sure what you're getting mad at me about.
Onto your 500lb deadlift = strong. Yes, someone that could lift that (or their bodyweight's equivalent) would be thought of as very strong. So would someone that could squat that, or pull-up/dip with 80+lbs of weight attached or any other potential measures. I DO agree, that a deadlift is an awesome all-around measure of strength, as someone with a big deadlift likely can do some of the above mentioned.