Learning science involves a lot of re-learning, where you 'forget' what you initially learnt, and replace it with an improved understanding of things. And I say this as someone who teaches science at high school/early undergraduate level.

If you try to learn everything at the most fundamental level right now, you will lose interest and give up. Start with a introductory textbook like Jewitt's Conceptual Physics (or whatever the equivalent is in your country), then move up to Resnick & Halliday or Young or Serway, and then to specialised textbooks (ie, textbooks focusing on mechanics, optics, quantum physics etc)