Need help with originality.

I like to use a combination of theory during improv and writing down whatever hits me hardest. Might want to record your ideas, continue working on your theory, etc. and eventually you'll get it.

(Secretly, I'm not that great of a bassist either though.)

 

Here are some TB threads you may want to check out:
~Getting creative
Where does creativity come from?

Creating bass lines
Target Approach
Walking bass line examples
Ed Friedland on walking bass lines

For a jam
Jammin'

Playing scales

Playing behind/ahead of the beat
"Feel"
Playing "in the pocket"

 

Originality.... hmmm..... First of all, you have to consider the source of who is telling you your ideas are crap. I put my bass down for 5 months one time because I got a bad comment. It just depressed me and I believed him.
Here's one technique that I use that is pretty fun. Take a song that you think is fun to play that has a cool bass riff. Then use the notes and pattern in that song to make it something completely different. I did this with several zeppelin songs and nobody would ever guess that is where I started from. For some people, having a good reference point to start from helps get you going. Think about a writer starting out a book with a blank first page. He might be driving down the road and see something that gives him an idea for that first sentence. Thats pretty much what I like to do sometimes.
Just my 2 cents. Hope this might help you along.

 

The way you've worded the question seems slightly counter intuitive.

Sometimes when I'm writing, I listen to a song and hum a bass line (simple is key here so as to be remembered). Next, I try and reproduce what I'm humming in the vocal range of my bass i.e. 7th fret and higher (this is the range I hum in). Finally, once I have a solid basic idea that I can groove I try to re-work fingerings in lower positions and elaborate on the groove so as to compliment the melody/vocals/solo.

 

Yup, now every bass line I've hummed in my head might not have been original, but every one certainly was correct and usually pretty good.

 

The more music you know, the more ideas you'll have in your head. Listen to all (make that ALL) kinds of music. Any music that you like, play it on your bass... that would be melodies, bass lines, chords, rhythms, music from any style or era, anything. Eventually you'll start putting all of it together in ways no other musician would.

 

The more you write the better you'll get.
I get maybe 1 good one out of 10 ...If I'm luckey!

 

It is important to be patient with yourself. Sometimes your ideas don't seem great at the beginning, but don't give up there. Write them down and play around with them. Also don't be so judgmental about your creativity. Write down all of the weak ideas you have. Usually, if I'm stuck on a part, I leave it alone and come back to it after a day or so. Very often that will open up my imagination. The more you play, more ideas will come to you.