One wonders here if inherited in verse 5 might not be an error for inhabited, perhaps the result of an attempt to avoid the redundancy of “because of the many inhabitants which had before inhabited the land”. In verse 6 we get the word inhabited but without any redundancy: “because of the greatness of the destruction of the people which had before inhabited the land”. Both inhabited and inherited are visually similar, but since 𝓞 is extant for both words (inherited in verse 5 and inhabited in verse 6), one might conclude that Joseph Smith misread the text as he dictated it to Oliver Cowdery. Or perhaps inherited in verse 5 was prompted by the occurrence earlier in verse 3 of the word inherit:
On the other hand, the text in verses 5–6 is referring to the Jaredites as the ones who had earlier inherited the land—that is, received the land as an inheritance:
However, there is at least one other place in the text where the verb inherit is used more in the sense of ‘inhabit’:
Stan Thayne (personal communication, 11 February 2005) notes that the Oxford English Dictionary, under definition 3 for the verb inherit, lists a transferred meaning “chiefly in biblical and derived uses”, namely, ‘to receive, obtain, have, or hold as one’s portion’ (or, in other words, ‘to possess’). Besides biblical citations, the OED gives the following example (accidentals regularized) from John Milton’s Samson Agonistes (1671): “It is not virtue, wisdom, valor, wit, strength, comeliness of shape, or amplest merit that woman’s love can win or long inherit”. In Exodus 32:13, the King James Bible provides a good example where the verb inherit means ‘to possess by inheritance’ rather than ‘to receive by inheritance’: “and all this land that I have spoken of will I give unto your seed and they shall inherit it forever”. (The Hebrew verb in this passage means ‘to possess’.) Thus the occasional use of inherit in the Book of Mormon with the meaning ‘to possess’ is quite appropriate and should not be emended to inhabit.
Summary: Retain the occurrence of the verb inherit in Helaman 3:5 (as well as in Mosiah 10:3); there is evidence in earlier English, especially biblical English, that the word inherit meant ‘possess’, especially with respect to land.