One idea sits under these words: more, much, many. From it Hebrew builds the everyday רַב (great, numerous, the multi- in compounds) and רֹב (most of), then climbs to מֵרַב (the maximum) and the very large רְבָבָה (a myriad, ten thousand). The root even reaches finance: רִבִּית, interest, is literally money that multiplies. This is a geminate root: its last two letters are the same ב, so the second often hides inside a doubled consonant. Every word here is verified against pealim, niqqud included.
No verb survives in everyday use for this family, so this page is all nouns and adjectives. The verbal idea "to multiply / increase" is carried in modern Hebrew by the related root ר-ב-ה (לְהַרְבּוֹת, to do much). A root that lives almost entirely as nouns and adjectives is perfectly normal.
Same root letters, different noun moulds (mishkalim). The mould tells you the function: who does it, the act of doing it, or the thing produced.
Strip the prefixes, suffixes and vowels. Three consonants remain, and the meaning lives there.