I was at DLRP for just 2 days - May 27th and May 28th - solo.
The parks were not very crowded so did not see MUCH line jumping but one incident aggravated me.
3 boys - 10 -12 years old I'd say (old enough to know better!) - on Space Mountain. They just started running up on the side of the queue past everyone. Two got by me before I realized what was happening and so I stepped in the path of the 3rd and said "I don't think so". He looked at me a little wide-eyed but he didn't go any further, and the other 2 ended up waiting for him ;-) at the loading point.
At the same time, same ride, there was a middle-age couple behind me that kept trying to cut me off. I mean really - there was just one of me!
And as someone else mentioned, there was NO respect of personal space. I'm a bit claustrophic, so having someone 2 inches from my nose is not pleasant at all. The only help I had was I had a largish backpack on, so I just kept kind of turning in circles which left a nice little space for me - people who crowded me would keep getting hit by the pack and after several turns would step away. Of course, they must of thought I was loony, spinning in circles, but at least I could breath!!!
Had a great time otherwise - very very pleasant castmembers and no one seemed to mind my "american" accent