I'm going to deviate a bit from your question, since you asked a bunch of questions, and aim at the implied question underneath: "is there any hope for a non-expert?"
A Synology network attached storage device (NAS) provides reasonably good answers to the question "how can I have privacy and have some backups" without being a Linux expert.
It ships with apps that replace common cloud services with local backup equivalents.
It can also be configured to do local encryption before backing up to a cloud service, for data where disaster resilience is more critical than privacy (i.e. a library of family photos).
Edit: And as others have explained - we must always remember that the cloud is just someone else's computer.
Related code should go together as much as possible, for maintainability.
If this results in too much code together, it's time to think about other ways to structure the code so that each thing the user can do fits into as few files as possible, but not too many things the user can do share a file.