Facebook Ads and other social media ad platforms, for example, are pay-per-click platforms that do not fall under the SEM category. Instead of showing your ads to people who are searching for similar content like search ads do, social media sites introduce your product to people who happen to be just browsing through their feeds. These are two very, very different types of online advertising.
For a small business, it is better to start with Organic SEO because aside from it is a low-cost investment, it will build your internet presence gradually and eventually have a solid foundation in your own niche – provided that you are doing the right way. It is not bad to invest in non-organic. You just have to make sure that you are investing on the right campaigns and not on the overly artificial ways to gain traffic and rank. Avoid investing too much on paid advertising and instead invest on creating relevant and useful content.