The most basic camera, Pinhole
A pinhole camera is a truly simple camera. Anyone can build one with varying degrees of success. It is essentially a light sealed box with a tiny hole at one end, and an imaging surface (film) at the opposite end. There is also a flap of some sort to block the light when not in the process of making an image. They can be tiny or huge devices.
Because of their simplicity they have many limits in capabilities. You only have control of two things, when the exposure happens, and for how long. I suppose you technically have 3 controls, the ISO rating or sensitivity of the film used.
The size of the hole and its shape dictate the sharpness of the resulting image, as does the pinhole’s distance from the film. The pinhole camera works well because the tiny hole helps filter the light into a single path from the scene to the imaging surface. The smaller the hole the fewer potential paths a photon has to go from any given spot on your subject to the film. Thus the image is fairly clear.
I start with the pinhole camera with the hope that it draws a line between what is required for an image to be produced vs all the complex stuff we buy to hopefully enhance the process. In the end the camera’s job is to collect light and store it in picture form. This is not a new process, and really can be done in a very simple fashion.
1) To make an image you just need to expose film to light. To be able to discern detail in the image you need to control that light.
2) The smaller the opening, to a degree, the more of your scene, depthwise, will be in focus.
3) You do not need complex equipment to take pictures of value.