From the sounds of it, there's senior level work in the organization, you just have to position yourself to be the one doing it. I've had these kinds of issues in the past, watching the boss hand plum assignments to people with demonstrably less knowledge and skill. You just have to work with them all to ensure the business gets what it needs. Eventually, if you are the more senior person, you'll get more and more of the senior level work because everyone will be coming to you for it. But, as has already been pointed out, you'll need to be very cautious about not trodding too heavily on everyone's toes while you do this.