Well, your one report isn't going to likely do anything. Either your report will be redundant to the automated bot detection systems, or your report will be fed into a pool that employees will look at trends from to improve the automated detection systems (and potentially issue retroactive bans after they find a new target computational flag).
But yes, you should report, because it takes all of a couple seconds and does help improve the detection system. Do just keep in mind that Riot doesn't ban bots instantly when they're detected, nor do they ban them some set time frame after. This is so the bot owners cannot discover "oh, hey, the bots are getting detected when they do X, let's make them not do X" anymore, if that makes sense. This is just the reason you may see bots at lower levels - if they're detected in their first game, they still aren't going to be instantly banned so as to prevent that from happening.