As explained under Helaman 16:10, the 1830 typesetter removed most instances of the Hebraistic and in his typesetting for the latter part of the text. For some other instances of this editing on the part of John Gilbert, see under 3 Nephi 23:8, 4 Nephi 1:47, and Mormon 3:4. Here in Mormon 1:5, the printer’s manuscript has the and, and the critical text will restore it. We should also note that in this passage Gilbert could have also deleted the repeated subject pronoun I. For an example of that kind of editing on his part (where he removed not only the Hebraistic and but also the repeated subject), see under Ether 9:8.
Summary: Restore the original and before the main clause in Mormon 1:5; for this part of the text, the 1830 typesetter generally removed these non-English uses of and.