A hundred of most anything known in the Old World all in one place would have been a「conspicuous array」most likely, NUMEROUS. In English, one lot as a measure of count is or was equal to 100 items (for example, an「odd lot」was any number of company stock shares less than 100 prior to online trading), and that is perhaps why「a lot」and「lots of」are used in American English a lot [sic] to mean ALL SORTS, MANY, albeit a poor expression on a grammatical basis.
Given the inherently crass nature of virtually all other Chinese glyphs, another possibility is certainly no less believable than scholarly explanations: consider the elements as「lateral reciprocating rod motions, indicates extent」with「emphasis on a tonguing mouth, open-mouthed, conspicuous, white, blank, empty, staring in a stupor, to make clear, emphasis on reciprocating rod in orifice」as the average count of reciprocating strokes needed to produce a「conspicuously white rod」and its discharge, to clear the inner pathway, to cause a torpid state of being, and so on as ONE HUNDRED. Leave it to the dynastic Chinese sages to conduct such a research study in order to report the average results in this glyph. Moreover, it should be fairly easy to verify their findings at home. Japanese pronunciation equates this glyph with the「upper thigh」also, for what that is worth, in case any male in Japan has some difficulty locating where to stroke. Any other suggestions are welcome to explain these elements as ONE HUNDRED.
Significantly, this is a decidedly male count only, as the female equivalent increases by an order of magnitude to one thousand, naturally…see 千 and its used-in glyphs for all the details.
Some scholars claim that in the very old days of China, HUNDRED was indicated by a thumb pointed upward and did not always signify an obscene gesture (such as, 'stuff it up yer anus' or 'yer cock is this short' or 'y'all go and jerk-off now'), therefore, elements of「one rod segment arrayed conspicuously white whilst in a state of torpor」meant 100, supposing that all refers to a thumbnail, and the thumbnail refers to one hundred. Without question, this explanation requires some long leaps of inductive reasoning if it is to be believed, and seems apocryphal at best.

External source definitions …excluding politically incorrect concepts and other meanings deemed offensive today; may include extended definitions, euphemisms, and mnemonics)
Chinese: hundred; numerous; all kinds of
Japanese EDRDG: hundred
Unihan extended: one hundred; numerous, many

Used within names (nanori)
お　･　ど　･　どう　･　なり　･　ひゃっ　･　ひゅく　･　も　･　もんど　･　ゆ