My first cavalier, Pippin, is also timid. Nothing in his past accounts for it. It is just his nature. He is just cautious and has the motto, "better safe, than sorry." I always reassure him that things are OK, but I don't try to make him do something he doesn't want to do.
There is an upside to this personality. He is my best behaved cavalier. He follows commands well and he is an absolute dream off-leash.
I think you will see that having Davis with his own distinct personality will be really fine.
Charleen and Cav's: Pippin (ruby male), Merry (b&t female), Luke (blenheim male) & Jolly (tri male puppy)