ConvertKit doesn't have separate lists (unlike more traditional platforms like MailChimp and Campaign Monitor). They way you separate people into different buckets is through tagging and segmenting. Having everyone in one list makes it very flexible as people can belong to multiple segments.
So for example, if you want to easily identify those who signed up to each landing page, you could have a tag for each landing page and apply it in an automation.
Or if you want to send specific follow up emails to people who signed up to a particular landing page, you can create a sequence. And then add people who sign up to the landing page to the sequence in an automation.
Does that help?