A small number of characters began as pictures. Most everyday characters are compounds. The usual modern pattern is a semantic part plus a phonetic part: 河 uses water plus a sound clue.
Traditional six-fold classifications (六书) are a historical toolkit, not a lab procedure. Teachers still use them because they give learners a way to remember graphs.
Why this matters for conversion
Simplified forms sometimes keep the phonetic and drop strokes in the semantic part, or the reverse. That is one reason a one-to-one mental map fails. Dictionaries do the mapping instead.
See also pictographs and radicals. For living standards, return to Simplified vs Traditional.