Knowledge is necessarily more fundamental than whatever we call perception, memory, introspection, reason, and testimony. Thus, these five items should indeed be regarded at best as sources of knowledge, and then only potential sources of knowledge.
And then of course there is a snag. Suppose you want to say that perception is a source of knowledge, then of course the question comes: How do you know that?
This suggests that these five sources are not sources of knowledge but sources of belief. I may be able to consult my memory of yesterday, but this does not imply that I will thereby know what happened yesterday, not even to myself. All I will get is the belief of what happened yesterday.
There is just one form of knowledge which we cannot deny and this is the knowledge of whatever subjective impression we have: impression that the sun is shining? Maybe the sun is not in fact shining but I sure have the impression that it is. Impression that I am in pain? I may be wrong to infer that maybe I cut my finger or something, but I cannot deny that I have the impression of it.
So this means the only source of knowledge is subjective experience. Our subjective experience gives us knowledge of our memories, perceptions, reasons etc. And then we usually proceed by believing that these sources of belief are truthful.
There are all sorts of views on the sources of knowledge, including divine revelation and what not. Your list of five is missing intuition for example, even though it is one of our major source of belief, one we use even more heavily than memory or reason. Maybe you could put down intuition as a species of introspection but no, this is not the same thing at all.
Perception, does it include "feelings" and "sensations", which provide us with beliefs about our own body?
Does "reason" include "logic"? Presumably, yes, but logic, nonetheless, is distinct from reason.
These different sources of belief are essentially contingent to us being natural cognitive systems. This list of five sources sounds like the list of the four fondamental elements, air, water, earth and fire. Not exactly entirely false, but somewhat naïve. A first approximation. Knowledge is more fundamental.