For Actuarial Science, the obtaining of a job/internship is going to be based more on the number of actuarial tests completed prior to either applying or graduating
Granted the GPA needs to be competitive but the school you graduated from in this field is not as important
A small school in PA, Lebanon Valley has many students go on and get Actuarial jobs
Finance is a different story all together
As your question asked, you are talking in generalities so here the school is most important
Certain Wall Street firms only recruit at certain target schools so if not at one of those schools the chance of working there is drastically reduced
Once again, certain jobs will have minimum GPA requirements but if met you have an opportunity
I agree also that ECs then play a big part in differentiating applicants
Some firms love varsity athletes due to time management skills and the ability to work in a team atmosphere
Networking, people skills then comes into play in getting the interview and advancing in the hiring process
Good luck