I learned about the equilibrium constant. Now, I've seen that the equilibrium constant of burning is extremely small $(K \ll 1)$. here, I have a question. you see, $K$ is still NOT 0, which means that the forward reactions happen at least a tiny bit. Then, shouldn't we see some parts of anything burning at least a little bit?
but I don't. Am I misinterpreting $K\gg 0$ or missing something?

No, you are not misinterpreting the concept of an equilibrium constant or missing something.

The fact that $K$ is very small for the combustion reaction does indeed mean that the forward reaction happens only to a very small extent in comparison to the reverse reaction, which is why most substances do not ignite spontaneously under normal conditions. However
why don't we see anything burning continuously? I know this question might be stupid, but I really want to know.

You are correct that the equilibrium constant for the combustion reaction is very small, typically in the range of $10^{-14}$ to $10^{-30}$ depending on the specific reaction. This means that at room temperature and atmospheric pressure, the forward reaction (where reactants are converted to products) is many orders of magnitude slower