I can't download and update my apps

I had the same problem on my older phone and I don't exactly remember but I think factory reset did the job. Like backup the photos n other then clean reset everything.

Another recommendation is that buying super cheap phones is not worth it and I know that the financial situation of many people does not allow that I was in a similar state but I decided to buy oneplus 3t when it was launched. About 460 usd not exactly cheap but till date I have never had any problems on the other side my mom bought yu5040 from yureka about 140usd just 5-6 months ago and it's already having problems.
So long story short don't buy super cheap phones

 

Google Play Services is the Android equivalent of Systemd.

And not only it's bloat, it's likely what takes more internal storage, and if it doesn't have enough, it takes your whole phone with it. And its hunger for resources keeps increasing with every update.

So, you better have a phone with a good amount of internal storage, otherwise the only way to chip down resources would be rooting it.