Coot, you're just scratching the surface of things. I won't say more as this game has spoilers galore. Keep trying to get PDA's. Explore all the beacons that get displayed after you receive radio messages. If there are no more radio messages left and you're stuck with nothing left to do, go deeper..never stop going deeper. Won't say anything more.

I have the Cyclops and it is pretty interesting. It's like a portable base, the only downside is that you can't put a nuclear reactor inside it. Don't waste your time just trying to get the cyclops, it's an awesome toy but you can live without it. It's mainly just a way to speed up transport of your PRAWN or Seamoth to certain locations, or have a central storage area so you can shuttle back and forth with your other vehicles loaded with materials.

Try the PRAWN suit and upgrade the depth module for it, as well as the jetpack upgrade so you can move around more quickly.

Use your scanner to scan random fragments left around the bottom, you'll often find new technology blueprints that way. Build yourself a nice base with lots of modules inside it, reactors, mod stations, moon pool etc. All of this will help you feel like you're working toward something. Some of the vehicles you can build are out of this world.

Make sure you've updated the game as it's changed a lot since I first got it in 2016. It is really well polished now and I don't notice any bugs at all, and the story seems to have been developed more.

The alien more complicated than you are thinking. Just keep exploring the deep, follow the beacons and eventually you'll start coming across stuff that blows your mind or browns your underpants.