Some simple takeaways from DeRouchie/Garrett, 349-360:

The Hebrew text was originally written only in consonants, though it was pronounced with vowels (of course). Then come the Masoretes around 500-1000. This small group of Jewish scholars developed a system of vowel pointing, cantillation marks, notes, etc. which make up the Masoretic Text.

The Leningrad Codex was the earliest complete MT manuscript, around 1000. This is how we have our standard Hebrew text today.