What’s a better term for "stupid" user?

A common term in the design world is:

Design for stupid.

Another one is the acronym KISS which stands for:

Keep it simple stupid.

or

Keep it stupid simple.

The logic in these statements is that if we design a product/experience/interface/etc. to be easy-to-use and work well for "stupid" users it will therefore work well for most users. However, we wouldn't blatantly call these users "stupid" to their face. So for this user group that requires extra assistance, what is a nicer non-offensive word to reference them?

These users tend to have difficulty in using a product/experience/interface/etc. due to a lack of experience/knowledge/common-sense/know-how/logic.