It is not complicated to understand. First of all, all cells in the human body (except sex cells and eggs, but babies get nutrition from blood vessels-umbilical cord) get nutrition from blood, which starts from the initial cell division. The human body is similar to a factory, and the task of the small intestine is digestion. This is very much like a human factory, where products are processed, handed in and bought back from the market (but some people take them directly from the production line). However, the cell is a loyal servant, and has been completing the task entrusted to it by genes, that is, obtaining nutrients and then giving them to the blood. However, some cells "rebel" and the immune system can also act as a "national defense force" to "counter-rebel". They will automatically treat them as enemies and attack them (to be exact, eat them) and these cells have a particularly famous name-cancer cells.

Therefore, the nutrients of small intestinal villous epithelial cells come from blood, which is due to human genes and their functions. However, due to physical reasons, such as water, small intestinal epithelial cells are directly absorbed.

I wrote this myself. I hope I can help you. You can ask me if you have any questions. Thank you!