The Trunk

extrude the inside of the legs inwards

scale in the vertices until they are almost touching

carry on extruding upwards and keep the vertices to your reference.

carry on until you get to the neck, stop there and dont carry on at the shoulder.

move in the vertices to round out the trunk

at this stage you should add in a few edgeloops and give your model a bit of form, shaping out the main muscles like chest and back muscles.

select where the arm comes out of the trunk and extrude outwards, rotate the face and follow the ref pic

add in a few more edges arround the elbows and towards the wrist.

if you cant see your reference picture properly go to shading and select wireframe.

press 3 to see how your model should look like, the big crease in the middle is there because we havent merged the two halves.

extrude the neck upwards