Loh berarti yg buat soal apa manusia bukan?!
In the other sentence "menganggap kalau" was accepted, here only "menganggap bahwa" is accepted. Why?
Both are understandable by native speakers, but the correct one is "bahwa". Use the correct one :D
in my understanding, the 'that' in this sentence can be 'bahwa'/'jika'/'kalau'