How can I get the bass sound at the beginning of this type beat? It seems like it should be so simple but nothing sounds right
That is a drone
The typical 'engine-like' variation, is created with flanger, or a special filter: Coomb. LMMS has a Coomb plugin, but it is difficult to keep 'sane'. It like to fluctuate a lot.
Sine+either a deep square, or saw, is a good starting point for the waveforms.
ZynAddSubFX (zasfx) has good fanger-fx, and even pr. voice, so interesting interactions can be made, but zasfx cant be automated, so a good VST would be my choice, and that means Synth1 :)