With Twitter imploding it's worth taking a look at alternatives, and another look at Mastodon if you haven't already. Just a brief summary:
1. It is Twitter-LIKE, but it is definitely not Twitter. There are some new things you'll have to learn and get used to; but while having to learn them is annoying upfront, they are simple things and you only have to learn them once.
2. The main things that are like Twitter are: you can make posts and follow people. You can retweet their posts (it's called a Boost). You can like (Favorite) posts. You can use and search hashtags. You can search for people by actual name and by @name. You can post links and images and (I think) video clips.
3. Your feed is not algorithmically curated. Your Home feed is just posts by people you follow, and posts they've boosted from other people. You can also sort the people you follow into custom Lists and read each List's feed separately if you want - prolly not especially useful until you're following a LOT of people.
4. Liking/starring/favoriting someone's post adds it to your favorites list and sends a little notification to them that you've liked it; but a post that gets a lot of Favorites doesn't "show up higher" in anyone's feed because again remember, there's no algorithm that cares about something like that. If you want to boost a post's visibility, Boost it!
5. Search for some hashtags to find posts and people to follow. Search the #followfriday hashtag to find whole lists of people to follow. ^^ Put some hashtags in your profile, follow randos who share your interests, and follow people back who follow you out of the blue - you can always unfollow them later if they turn out not to be your mesh. The more you're followed, the more people will see the posts you make and the posts from others that you boost, and that's how everyone's feed comes alive.
6. The big thing that's not like Twitter is that instead of everyone on Mastodon all being in one basket, they are divided into many baskets called "servers" or "instances", that have their own admins and mod teams. However, this only LOOKS like a complication. People from different servers can still follow each other and see and boost each other's posts, the only difference you'll actually see is that the server-name at the end of their @-name will be different. Servers CAN function as a sort of smaller community within the larger service - but you don't have to worry about that right now. If you're new/just getting started, you will have to choose a server but just choose one of the mega "General" servers with thousands of people in it, like mastodon.social or mastodon.online. You can migrate your account to a different server whenever you want without too much effort (and still retain all your posts and be able to talk to all of your follows/followers like before), so as a newbie just consider servers to be like an advanced feature that you can look into later when you're more comfortable.
7. NO ADS
8. Elon Musk is not on Mastodon
9. Elon Musk cannot buy Mastodon even if he wanted to, and nor can anyone else, real or corporate.