The most common point of entry of water into a basement is through the cove seem. This is the seam where the footer sits on top of the wall as show below.
This ‘cove seam’ where the separate sections (the footer and the wall) are poured at different times (the footer is poured first). This is the way all belowground foundations are built. The problem is that this always leaves a small seam where the two footer (first pour) and the wall (second pour) meet. As water stands outside the foundation as in the picture below, it penetrates through this seam. This is why most foundations are damp/wet across the entire wall floor seam (cove seam).
The problem in most finished basements is when you place drywall and framing on these same problem outside walls. It is a recipe for instant mold.
Water is a very small molecule (see Amazing Water). One of the smallest actually. Trying to seal these walls off with painting products or trying to dry out the rooms with standing water using dehumidifiers is not possible.