The reality is that bitcoin first appeared on the earth a decade and few more years ago on the earth. It's planning might have started way before that so that the inventor was busy coding the blockchain and it's logics. Ideally it started, and it never looked back to this date. The reality is that, there is more than trillions of dollars which are being spend on the blockchain and the enormous volume is driving the price of bitcoin to the new goal.
Now, what bunch of peeps think about the bitcoin does not matter here. If invisible reader is here to gain more knowledge about it, then read the above para twice and empty your bank into crypto before its too late.
The reality tells me, bitcoin is now way sophisticated asset than it was a year ago and it would far more lucid a year after this. So don't argue, because we would be just wasting the time and nothing else.
The idea started even before 2000's, maybe by satoshi himself, maybe someone who is totally stranger who just checked, but if you check the "e-money" world, we had many many periods before bitcoin that had emoney methods.
However, blockchain basically created something that is non-penetrable and also decentralized which gave its power. Look at usdt to see the difference, if the first coin was USDT then we wouldn't have this situation, we would have something that is totally different, why? Because it is centralized and pegged, then we wouldn't have crypto at all. The reason why bitcoin became this famous is the fact that it is decentralized and it is totally owned by the people and nobody else.
You are right, if there were no BTC there would be nothing, that is why many say that BTC is the King, he is the boss and that is why it is the total dependence of altcoins by BTC. I have seen many talk that altcoins can survive without BTC and no, it is impossible, it is like the example you give with USDT, USDT is not totally USD, it has a combination with crypto, because that was the last report made. .
However, currently BTC is reaching governments and banks with more force, USDT is only seen as one more stablecoin, I believe that the reality with crypto resides from that point of view, where it could have had many origins, but it really was created since Satoshi Nakamoto came out.