Is there anything as simple and straightforward as Skype is (or used to be)?

Need to be able to chat, share files, share screen

Whatsapp does some bit s but not all, not sure what else there is or how good it is

Do you require the solution to work across multiple platforms; iOS, Android, Windows, MacOS?

Is end-to-end encryption important for your use cases?

Microsoft's intention was to transition Skype users to Teams. Is there a reason that Teams isn't suitable for your needs?

Don't get me wrong, I personally loathed Teams. When it came out, there were so many rookie mistakes in its UI and design that I was convinced it was written by MS interns. But I got used to it, and it was tolerable after a while. It's been over a year since I've had to use any software like that, so I don't know what its current state is.

I'm wondering if there's some basic thing that Microsoft is ignoring, which left you unable to migrate to Teams. If so, I expect you're not the only one. But googling tells me that there's a free version of Teams, and that you should be able to just log into it with your Skype credentials. That could be incorrect or outdated information. I know that the free version of Teams has some limitations, but skimming the list of limitations, it sounds like it's not a big deal. For instance, you can share a screen, but you can't do whiteboarding. You can have video chats up to 30 hours long, but group video chats are limited to an hour.

Needs to be multi platform, I'm not worried about encryption but some of the people I work with might be

It is dogshit, and overly complex for my needs even if it wasn't so bad.

If Whatsapp had screen sharing then it'd probably be OK

Jitsi? https://jitsi.org/

Never used it, but it I've seen it recommended by someone I respect.