First, "moving apps" to the SD card is a misnomer. Someone discovered that you could appear to do that a long time ago, and everyone's been doing it ever since - but there's a problem, especially in the last couple of years. The way apps are being "written" these days (a lot of them aren't - they're being built by "app-building apps"), the app has to be moved to the SD card in separate little pieces. Each piece has to have a link in internal storage pointing to where it is on the SD card. (Years ago, people actually wrote apps and they'd be in 2 or 3 chunks.) So now you have a link left in the phone that's as large as (or even larger than) the piece of app moved to the SD card. You save very little, if any, internal space. (If the pieces are smaller than a link, you actually fill internal storage up by "moving an app to the SD card". And you're putting the app on storage that doesn't last as long as the internal storage in the phone.
So moving apps to the SD card is a bad idea.
The phone, even though it was released in July 2017, is a very small phone by today's standards, when 64GB is usually the smaller of two versions of a phone, and many phones come in a 128GB version. (And apps tend to fill all available space. A developer isn't going to be working on an emulation of a 16GB phone, he'll work on a 128GB emulation, so if the app builder is sloppy, who cares - there's plenty of room in the phone.)
A 16GB phone today is good for use as a phone, for texting, for connecting with sites on the internet, for keeping pictures, music, videos, documents, etc., on an SD card - and to keep a few needed apps more than it comes with - but only a few. Uninstall any apps you don't need (after moving them, maybe one by one, back to the phone). Once you have at least 4GB free in internal storage, restart the phone and it should work. If you can't do without most of your apps, you just have to get a phone with more storage.