These claims are misleading.
1. In its latest intake, Oxford accepted a marginally lower proportion of BAME (Black and Minority Ethnic) students than the average for the Russell Group universities ( 23.6% versus 23.7%). The proportion of female:male applicants that get accepted is also slightly lower than the average for Russell Group universities overall (54.2% versus 55.1%)
https://www.ox.ac.uk/sites/files/oxford/Admissions%20Report%202019.pdf2. It is hard to determine the relative ease of getting an offer. Oxford makes offers to 17.8% of applicants. Cambridge makes offers to 24% of applicants. But successful Cambridge students tend to have marginally higher A Level grades (95% versus 90% have A*AA or better). The average successful Oxford applicant has around 8 A*s at GCSE, which rises to 10 for Medicine.
3. In your personal statement and at interview, the expectation is that you will provide some evidence of wider reading in your chosen subject, but "extracurriculars" like sports and hobbies are of no interest. Once admitted, there remains absolutely no interest in whether or not you decide to to engage with societies or sports. It is entirely up to the individual whether they live in the library 24/7 or launch themselves into a career as a world class egg and spoon racer. So long as you do OK in your academics, you're good.
As far as the OP's concern about anti-Chinese bias in the Biological Sciences department is concerned, that something I have never heard before. This FoI request shows that in 2018, 6 of of 81 Chinese national applicants for Biology got offers (7%), and in 2019, 4 out of 51 got offers (8%) The overall success rate for all international applicants for all subjects is around 9%, so it looks like Biology is similar.
https://www.whatdotheyknow.com/request/undergraduate_admissions_statist_14