Adwords is very important for SEO because it feeds Google with information regarding the user experience regarding your targeted keywords.
The landing pages for all your ads have to be exactly what the visitors are looking for to avoid high bounce rates and to teach Google that your website is, in fact, relevant for the keywords people are searching for.
Creating several ads for hundreds of keywords, all pointing to a busy and confusing website homepage can hurt you in the long run. Visitors will hit the back button if they don’t see right away what they were looking for. Don’t count on them to “look it up” once they land on your home page.
Instead, specific ads need to be created for specific pages. Those pages need to answer a specific problem, targeting a specific key phrase. Some digital agencies don’t like doing this because it takes a lot of time. It may be tedious but it works.