Lately I keep hearing people talk about block builders, bundles, making it seem like if you don't understand, you'll get "eaten."

I personally think retail investors only need to know this much: the transactions you send may not get on the chain in the order you want, and in the process, someone might bundle, cut in line, or even treat you as part of an arbitrage.
So don't push hard in low liquidity, don't use too loose slippage, and try to use reliable routing/private transaction entry points (if available), to avoid getting squeezed and having your mindset blow up.

The deeper stuff like market construction, auction mechanisms... honestly, they don't help much at the moment I place my order.
I see complexity as an enemy: if I can use a rule to protect myself, I’ll use that first.

By the way, recently the testnet incentives and point expectations have stirred up emotions again, and the more speculation about "mainnet issuing tokens," the more congested the chain gets, and the easier it is to see bizarre transaction prices...
Anyway, I’ll slow down first and not get caught up in the narrative.