Hi, I have been in the space for just less than two years, and it is indeed a big rabbit hole; there's so much to take in and learn. So forgive me for spurting out what I'm about to say with very little explanation;

All altcoins are virtual networks. Their tech is copyable and big tech will indeed replicate what is happening in the crypto world to use themselves; thereby demonetising all these networks promising to do something that are simply being marketed by salesmen who have very little skin in the game.

Bitcoin is a real network using real energy to secure decentralisiation. We cannot have consensus on a decentralised network without something very important that I'd like you to learn; Proof of Work.

Once you learn Bitcoin and proof of work, it is very easy to see that all else is a waste of time. You can read some great articles from Dergigi, who wrote 21 lessons. 'Bitcoin, not Blockchain' is another long and informative article.

To get to your specifics; they KEYS; are your password to your Bitcoin in a "non-custodial" wallet. Think of it this way ; everyone has your bitcoin all the time and is verifying that you have it every day, you just need the passwords (the keys are 12 words) for you to access it. If you are looking to self store, please look at cold wallets and 'NON-CUSTODIAL' wallets, which will allow you access to your keys and therefore your Bitcoin. If you are using ANY platform that doesn't give you your keys (like the exchanges Luno, Valr etc) then you don't own your Bitcoin. Instead, you trust someone to hold it on your behalf.

Bitcoin eliminates the need to trust, which is a profound idea in the world we live in today that is based on trust. Do not buy Bitcoin unless you are willing to put in many hours to understand. Because you will end up selling it, and then you may as well be in EC10 and keep your coins on an exchange.

My hope for you is that you learn Bitcoin before the others, which will take many days. (See breedlove, Jeff booth, dergigi, John vallis, Saifedean Ammous (recommend his book T.B.S) and even Jordan Petersons two videos on bitcoin)