The threshold for having learned something is subjective, at least in the context of software development.

If the intent is just to attain a basic understanding that enables one to complete projects and pass muster as an intern/junior developer, then it's likely possible with enough effort.

If the intent is to do a "deep dive" on each topic, or even attaining mastery during the course of a summer, then that's another matter entirely.

On that note, the concept of mastery is similarly subjective. Even the lowest definition of mastery for a single one of those topics lie far beyond the timescale of a single summer, at least for most people, and especially if they lack previous experience. Fortunately, very few people are masters of anything.

> If the intent is just to attain a basic understanding that enables one to complete projects and pass muster as an intern/junior developer, then it's likely possible with enough effort.

For me personally, that's the understanding. Enough to get a job as an intern or junior dev.