how do you write a melodic bass line?

[tbird99]

I love the intro to like aeroplane by rhcp and penny lane and I'm trying to write something like that I hate lines that repeat themselves a Lot so as of now I'm messing around with minor pentatonic scales like the high g scale and doing g a b then after I do that repeat it but add c# , then go up a whole step and do that the go down 2 steps and then play the 1st , 3rd,and 5th of f then play f then add the f to the 1st,3rd and 5th, this is my first complex song sorry for how bad this will be to understand I don't know how to say it any other way so that's gow I worded it p.s. then is all played fairly fast

 

[tbird99]

I would say in the pentatonic scale park the first three notes played in in one beat then when I add the fourth note it is a quarter note