Hi Ben,
I would suggest that you start with a 2nd hand camera like a D3200 or even a D3000 or D3100 and the kit lenses 18-50mm and 55-200. They can be had very cheap in 2nd hand and will resell after a year with a limited loss or no loss at all. If you have 100$ left, buy also the cheapest Canon Selphy you can find to print the pictures you like and look at them "in real life", not only on a screen. If you still have 100$ left, buy the Nikkor 35mm F1.8 DX.
Put the camera on A mode and start shooting. In the beginning, take the same picture at various apertures. When looking at your pictures, and those you like on books or online, and asking for feedback, you will easily understand when to change aperture, speed or ISO to get something you prefer. If you shoot regularly and check your pictures often, in 6 months you will have the required understanding to start knowing what to do. You will soon realise if the limitation of the camera you have is a problem and, if needed, will be ready for a next model.
Resell the D3X00 and buy 2nd hand again a D90 or better a D7X00 and a faster aperture lens of your preferred focal length. At that time, you will know which one it is by simply looking at the most used focal length of your preferred pictures. You will then also be ready to experiment with a lot of old Nikon AF or manual lenses, which these cameras allow. They are much cheaper than modern lenses but are often of really good quality. They will help you learn further. They are also no risk: if you buy one that you don't like, simply resell, they don't lose 2nd hand value.
After 6 months or a year, you will know if and why you would need an up to date camera.
Don't hesitate to post pictures or ask questions. This is a friendly, non judgmental community, with lots of skilled photographer, professional or not. For me, this forum has been the best source of help and knowledge. Every time I had a problem, several people step up to help me with advices or answers.
Good luck.