Werner Roth drew the Lorna the Jungle Girl stories in her title at Atlas from #1 (July/53) through the first two stories in #12 (Mar/55), without a signature. Her artist in #13 (May) was Jay Scott Pike, who signed his stories. The unsigned third story in #12, "Trial by Fire," has been attributed to Roth in the Grand Comics Database and to Pike in the Atlas Tales website.
The artist has been correctly attributed the Greg Knight solo story in #13. He's Bob Brown, who would pencil another Marvel jungle girl when Shanna the She-Devil guest-starred in Daredevil in 1974.
One writer did most of the Lorna stories I've seen so far. Don Rico is known to have written Jann of the Jungle for Atlas at some point, but whether he wrote the bulk of the company's jungle stories is a question I haven't answered to my own satisfaction yet.