You can call Oswald a lot of things, but I'm not sure wimp would be one of them. The guy was Marine, and he did basically defect to the Soviet Union and then return to the United States, both of which take a certain measure of personal resolve. At the same time, he appears to have been something of a petty tyrant, abusing his wife Marina both physically, and emotionally, humiliating her in front of her peers and trying to keep her both socially isolated from the Russian ex-pat community in Dallas and through keeping Russian as the language spoke in the home so that Marina and their kids would have trouble integrating into society (page 417 of the Warren Commission Report).

As for credible evidence of a conspiracy, there isn't much I'm afraid. While it is impossible to definitively say for sure, we do know that Oswald was at the scene of the crime, and owned the murder weapon. He fled the scene and quite likely killed a police officer to avoid apprehension, which again, suggest a certain level of complicity. He was also very capable of making the deadly shots, which were a lot easier than some subsequent fictional films have presented them to be.

In 1979, the House Select Committee on Assassinations did conclude that there was likely a conspiracy, but that was largely predicated on the basis of audio recordings made on a dictabelt from an open police motorcycle radio during the shooting which led some analysts to conclude that there was more than one shooter on the scene. This evidence however, has not stood the test of time and a subsequent evaluation of the dictabelt by the National Academy of Sciences (Report Of The Committee On Ballistic Acoustics, National Academy Press 1982) found that the recording was of sounds made 1 minute after the assassination.

Even the Zapruder film, probably the best piece of physical evidence from the tragedy, appears to show shots from the direction of the Book Depository, where Oswald worked, as explained by a forensic specialist testifying before the Rockefeller Commission in 1975.

So yeah, not really much in the way of substantial evidence of a conspiracy. There are a lot of anomalous things about the assassination, but as with any event involving so many people, there are going to be things that seem a little weird, or are unexplained. That's just the way it is sometimes.