The hosts were changed and made more realistic, presumably by Ford, after Arnold "killed himself" because he found out what ford was planning. This was 35 years ago.
30 years ago the park then went to shit with dolores going off the rails.
Ford thought it was fixed but Arnold is still "alive" as a dormant virus.
30 years later the park is again going to shit with Dolores going off the rails.
Bad cowboy said to Ford at the end of 5 that it would have all been lost 30 years ago if it wasn't for him. I still think he's the brother in law in the past.
The 2 timelines still make sense to me because Lawrence was alive in town after just being killed.
You just need to think they are not playing things in order. They make it look like Dolores is taken out there and then but she isn't.
Also Dolores and the others have been living in constant dejavu their whole lives so things are going to be re-lived over and over and whatever happened in the last update has given them access to their memory banks which confuses things for them and us because they don't age and they get wiped every time they die then remember again. (Like Thandie with her drawings under the floorboards)
DP thinks Dolores is the missing link/cause of tension between Arnold and Ford. They said in previous episode that Dolores was the oldest host in the park.(the first?) Maybe she was made in the image of someone they both loved who died in real life or something.