We have many affiliate link like below.
example.com/123.html
example.com/456.html
example.com/789.html
example.com/555.html
example.com/666.html
....more than 1000 URLs
All these links are 301 redirected to the main URL (example.com)
Will this affect our main page SEO Ranking / SERP Ranking?
It will/does NOT have a negative impact on your domain. Simple is that. It may even have a positive impact on your main page, provided the child pages were up to standard and of value and received backlinks. If not, they may not provide any advantage, but simultaneously will not hurt your SEO effort.
