Hi Paul,
I agree with Nicolas: not reaching the desired results in the SERP's can be quite a few things.
Also: you wrote that the site is has no penalties because you don't see any in the Google Console. Is there a chance that you might have had a penalty? If it has been your site all the time you should know i guess.
Why not turn this around: start over, read up on SEO-blogs and sites like this. See what is necessary to get your site te rank high in the SERP's.
Create kick-ass content
For instance: Start by creating VERY cool landingpages for long tail keywords. Wait some time and see what they do: are you able to rank that way? Not: then figure out what might be the cause of that. Maybe you do have a penalty..
In case you start moving up in the rank, copy the concept and create more unique and cool landing pages. For long tail keywords and this time for competitive keywords as well.
Links
Also: check your link profile. Make sure you can be found where your potential visitors are looking for you. Create backlinks. NOT in a spammy way! Just make sure you haven't missed a webpage that would make sense for you to be mentioned as well.
Social media
Every time you have created cool new content, make a very cool post for social media. Share it on Facebook and make sure people will share your post as well.
Hang in there!
Keep this going for some time and you will see result. More direct visitors thru the links, social media mentions and Google of course.
Just a couple of tips that you maybe able to use.
Good luck and: have fun!
Bas