That sketch looks a lot like early German designs for jet fighters. Plonk the engine down behind the pilot, run an intake duct around both sides of the cockpit (which is why the MiG-15 has the vertical divider in the nose), attach the tail as close as possible and fill the wings with fuel.
The American F-86 had the cockpit higher and used a single intake duct running below it.
Why later designs had the longer fuselage in the rear was mainly to move the tail back for better stability. Even so, the MiG-15 had more rake to the fin than the F-86 and put the stabilizer at its top to help more with stability.