No. Some ads can be created by more than one person (group input).
The purpose of ads are to grab the consumer's attention. While this sounds simple enough, there's actually a lot more to it. Companies put millions of dollars into creating ads. Aside from having a flashy ad, companies also look at demographics. They want to target the group who will spend the most money on their product. Ever notice that the "models" in many ads are young? That's because many ads are targeting the 24-40 age group. That's the age group that statistics show to have the most "surplus" cash that they are willing to spend. The 5-14 group are targeted by toy ads. The 35-50 age group has ads featuring families targeted at them. The 45-60 group (empty nesters) are the prime target for sex aids They are also targeted by drug ads, and ads for helping their senior parents.
Notice that many ads targeted to kids are full of vibrant colors yet have white backgrounds. This lures the eyes to the specific color (usually red). Ads targeted at teens and young adults are more "fuzzy" (fast moving) and have somewhat darker colors. This is to set mood (do your own thing, be your own boss). Ads targeting the 25-40 group have bold vibrant colors, are are many times humorous but dont move as fast as ads target to a younger group. Ads targeted to the 45-60 group are slower, mellower - relax, the kids are gone now you can take it easy.
Companies like catchy tunes. Music is a major part of memory. If a company can get at tune stuck in your head chances are you'll remember it for the rest of your life - and when you do, you automatically think of their product. Besides creating jingles, companies will purchase the rights to songs heard during certain eras. For example, companies are using songs/music from the 80's to "entice" the 35-60 crowd.
While some people may find certain ads insulting, one has to remember that companies are doing broad targeting with ads. Not everyone thinks alike. Plus, some people remember really bad ads. If someone remembers an ad - for whatever reason - then that ad did its job.
A catchy slogan or mascot works wonder as well - "Silly Rabbit, Trix are for kids"; "I can't believe I ate the whole thing"; "Flick your Bic"; "Where's the beef?"; "How many licks does it take to get to the center of a Tootsie Pop?", "It keeps going, and going, and going, and..."
Even if the product no longer exists, sometimes its slogan will still stay in memory - "It slices; it dices, it makes julienne fries" (Veg-O-Matic);