trying to understand how layer 2s work

the layer 2 rollup space seems to cause a lot of confusion, it is quite non-intuitive, possibly because we have decided to use poor metaphors, such as bridges

most people seem to see layer 2 as a separate blockchain entirely. you see comments that they don't care about scaling the rollups, they want to see etheruem scale on main net. but as far as I understand, when using a layer 2 your money never leaves layer1. also this is made worse by the holders of rival chains like sol who are financially incentivised to attack eth

from my understanding and correct me if I am wrong, if for example you want to bridge 1eth to arbitrum, what you are actually doing is locking 1 eth in arbitrums smart contract, which lives on the etheruem main net. after doing this you are given a token that shows up as 1eth on arbitrum. you could take advantage of lower fees and swap half an eth for 1100 tether. and arbitrum will update the state root on main net and in the arbitrum smart contract, you now hold 0.5 eth and 1100 usdt

there seems to be a criticism that because a rollup only has a single sequencer, its centralised and therefore could lose your money. but actually your money is still on ethereum and it should be possible to remove it by making a layer 1 transaction, if arbitrum were to shut down for some reason

it seems like the term bridging is wrong, that makes me imagine driving my car from ethereum land over the river to arbitrum land. but I think its more like a valet parking garage, you leave your car with them, get a ticket for convenience and could recover it any time with the ticket. or a cloakroom in a night club, a cash desk in a casino etc.

but from a user interface, it actually does seem like they are separate chains. have money on polygon and want to use GMX? can't do so without bridging. so its easy to see how the confusion happens. or maybe to all intents and purposes, they ARE separate chains until we can build some better ux to tie liquidity all together, or abstract it all away

if I'm wrong about anything please correct me, I am trying to learn the concepts myself

​