Are sales or third party marketing firms a good place to start.

I'm a recent grad from a non target school and I want to be either a trader or analyst, or something with a big future, but I'm only really getting offers for sales roles which I'm enthusiastically applying for. I've gotten an offer from Bloomberg, Wells Fargo, and BOA for sales positions, and nothing else really. I've also been offered third party marketing firm roles (Companies that get clients for actual investment banks). Are any of these worth it?

From what people I know tell me, it's a foot in the door, but is it really? For a lot of these positions I will be learning a lot about stocks and finance, but will it allow me to get a bigger position in the future? I've been applying to jobs at BBs and a lot of them do mention sales experience, by that is it only reserved to trading or general sales experience? I ask because a lot of the non sales jobs I've looked mention having sales experience.

Any Insight is appreciated.