"This interesting name, variations of which are Cobbe, Cobb, Cobson, and Copson, is of early medieval English origin, and is an example of the many early surnames that were gradually created during the Middle Ages from the habitual use of a nickname. In this instance, the nickname, or byname, recorded in Cornwall in 1201 as 'Cobba', derives from a term meaning 'lump', found in both Old English and Old Norse, and used to denote a large, well built, impressive man. The equivalent byname in Old Norse is recorded as 'Kobbi', and the examples of the surname Cobb or Cobbe found in the eastern counties of England are probably derived from this source. In some cases, the surname may represent a short form of the male personal name 'Jacob', from the Hebrew 'Yaakov', which is traditionally held to mean 'he supplanted', from the biblical story of Esau and Jacob."
More here if anyone's interested.
https://one-name.org/name_profile/cobb/