Yes, every cell in the past 2 or 3 billion years has come from another cell. As far as scientists know, life has not been newly created since the first cells developed billions of years ago. The process of going from the components of living things to living things is complicated and not well understood. The information necessary for one cell to become two cells is contained in the cells themselves. Therefore, the only thing that knows how to make cells is other cells.

Cell division is one of the most fundamental properties of living things because the ability to grow and make identical copies is one of the things that distinguishes living from nonliving things. Nobody currently knows why new cells don’t just appear, but these new cells would probably wouldn’t be as good as surviving as well established cells.

Interesting results of the fact that cells come from other cells is that any living thing that grow is still alive. So, an apple seed or acorn still contains living cells since it turns into a tree.

The only way we know of for cells to be made is for them to be created by other cells. Life had to start from something without cells once in the past, though, and I don't think we know how that happened, but all cells after that came from existing cells.

Yes, cells come from other cells. This is one of the properties of the basic cell theory, which states:

1. Cell only arise from pre-existing cells. (They cannot spontaneously arise).
2. The cell is the basic, smallest unit of life.
3. All life forms are made from one or more cells.

Scientists who contributed to the cell theory include Louis Pasteur Antoine van Leewenhoek, Robert Hooke, Francisco Redi.