1. Of course giving protein to Kenyan children is going to improve their performance at everything, that's not surprising to me. People need protein and if you're giving some of it to some of them who probably aren't getting plenty of it already, it'll help them. That doesn't directly have a bearing on whether a first-world adult choosing to consume only meat is going to improve anything for them.
2. Correlation is not causation, both meat consumption and overall life expectancy are going to be highly correlated with societal wealth. That's not surprising to me, it doesn't directly have a bearing on whether a first-world adult choosing to consume only meat is going to improve anything for them.
3. That's a social media survey of people self-reporting consuming a carnivore diet and asking them to self-report their health level. It's not surprising to me that they self-report that the carnivore diet is having good effects for them.
4. Correlation is not causation.

On average, participants who reported consuming meat regularly (three or more times per week) had more adverse health behaviours and characteristics than participants who consumed meat less regularly, and most of the positive associations observed for meat consumption and health risks were substantially attenuated after adjustment for body mass index (BMI). In multi-variable adjusted (including BMI) Cox regression models corrected for multiple testing, higher consumption of unprocessed red and processed meat combined was associated with higher risks of ischaemic heart disease (hazard ratio (HRs) per 70 g/day higher intake 1.15, 95% confidence intervals (CIs) 1.07–1.23), pneumonia (1.31, 1.18–1.44), diverticular disease (1.19, 1.11–1.28), colon polyps (1.10, 1.06–1.15), and diabetes (1.30, 1.20–1.42); results were similar for unprocessed red meat and processed meat intakes separately. Higher consumption of unprocessed red meat alone was associated with a lower risk of iron deficiency anaemia (IDA: HR per 50 g/day higher intake 0.80, 95% CIs 0.72–0.90). Higher poultry meat intake was associated with higher risks of gastro-oesophageal reflux disease (HR per 30 g/day higher intake 1.17, 95% CIs 1.09–1.26), gastritis and duodenitis (1.12, 1.05–1.18), diverticular disease (1.10, 1.04–1.17), gallbladder disease (1.11, 1.04–1.19), and diabetes (1.14, 1.07–1.21), and a lower IDA risk (0.83, 0.76–0.90).

https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-021-01922-9

That's just the first random thing I found. Again, I am sure that a lot of that has to do with the low quality of the meat available in modern factory-farm-driven societies. I'm just saying that if you're advocating for people eating meat, and they live in that type of society, they're going to be fucking themselves up by eating lots of the type of meat that is available to them in that society.