Of course Kannada evolved from ancient Tamil. If you know both the languages, you can easily find root words for most current day Kannada words in ancient Tamil sangam poetry (like ooru=>oor referring to town, kaaveri=>kaaviri, etc.) https://en.wikipedia.org/wiki/Dravidian_languages
Kannada, Telugu, Malayalam all have higher degrees of impact due to Sanskrit but they are all dravidian languages, derived from ancient Tamil.
Your Wikipedia link disagrees that all of the Dravidian languages are derived from ancient Tamil. It describes them as common descendents of Proto-Dravidian. It cites the attested literature of Tamil as being 2,000 years old.
Kannada, Telugu, Malayalam all have higher degrees of impact due to Sanskrit but they are all dravidian languages, derived from ancient Tamil.