How can you say the lobefin fish were the ancestors of amphibians?

Hint: During the period of Devonian amphibians were evolved from the fish called sarcopterygian fish. This sarcopterygian fish has lungs, bony limbed fins, and special features that help the fish to get adapted to the dry land.
During the period of Carboniferous and Permian, amphibians diversified and became dominant. Later reptiles and other vertebrates displaced the amphibians.

Complete answer:
As we all know that the first animals to attempt from aquatic life to terrestrial mode of life are amphibians. Amphibians essentially are the very much the earliest tetrapods descended from fish like ancestors during the Devonian period from lobe-finned fish named sarcopterygians.
Lobe-finned fishes, kind of such as coelacanths and lungfish, essentially were the most diverse group of bony fishes in the Devonian in a major way.
The fins evolved into the legs of the first tetrapod land vertebrates, amphibians, which particularly shows that amphibians particularly are the first animals to attempt from aquatic life to terrestrial mode of life, which is fairly significant. They also actually possess two kinds of dorsal fins with fairly separate bases, as opposed to the particular single kind of dorsal fin of ray-finned fish, which is fairly significant.

Note: Amphibians are vertebrates that are small in size. For amphibians to survive, all they need is water or a moist environment.
Frogs, salamanders, newts, and toads are species that are included in the group of amphibians.
Amphibians have a special skin thought in which they absorb water and can breathe and also they have skin glands that are helpful to produce proteins.