AMCAS publishes a document that includes a survey of medical school admission offices which shows what factors adcomms consider important.
See p. 15
https://www.aamc.org/media/18901/download
This table–Table 1. Mean Importance Ratings of Academic, Experiential, Demographic, and Interview Data Used by Admissions
Committees to Make Decisions About Which Applicants Receive Interview Invitations and Acceptance Offers– ranks academic metrics, experiences, demographics and other data into highest, medium and least important categories.
In the least important category under academic metrics:
Degree from a graduate or professional program
Completion of challenging non-science coursework
Ungraduate major
Selectivity of undergraduate institution(s)
Non-science undergraduate major
So the undergrad attended has some importance but isn’t a major factor in deciding who will be interviewed and accepted.
The initial round of applicant screening is tyically done a computer program which assigns a rank to the application based upon sGPA, MCAT score and demographic information. Highly ranked applicants are given priority consideration for a human eyes review. (Typically applications are sent to 2 volunteer readers for review and scoring… so the luck of the draw plays a part in how an application is perceived.)
While some selective undergrad institutions may have some name recognition among some application reviewers, how much that name influences their perceptions of the applicant is unclear and variable.
Adcomms are not a monolithic group, but a group of volunteer faculty, staff, med students students and community members which changes from year-to-year. The adcomm members use a scoring rubric to rank each applicant under consideration for admission on how well each fulfills the The Premed Competencies for Entering Medical Students | Students & Residents and the institutional needs of the school.
BTW, the lowest acceptable GPA and MCAT score for a particular med school is proprietary information and not publicly available, but in general is much lower than most people think because med schools don’t want to screen out career-changers, military vets, low SES, disadvantaged, and other non-traditional applicants.