Igbo is a member of the large Niger Congo language family that shares tones with many other languages including Ibibio and Yoruba. It even shares tones with more distant languages such as Chinese. In fact, the Igbo first, fourth and sixth tones (as used in the UI dictionary) are almost identical to the Chinese first, second and fourth tones respectively.
The Chinese Kāfēi (coffee) has the same tones as the Igbo akwa (cry); the Chinese rén (person) has same tone as the Igbo nee (look as a command). The Chinese mà (curse) has a similar if not the same tone as wa (which means no in some Igbo dialects).
The reason why Chinese sounds very different to Igbo and other Niger Congo languages could be in part due to how the tones are used.
Unlike Chinese tones, tones in Igbo change a lot within sentences. The first tone (which we share with Chinese), for example, frequently becomes a softer third tone in Igbo, which is when the third tone becomes a fourth tone.
Tones also merge with each other forming new ones. See for instance Ada (eldest daughter), with tones 2,1. When ada merges with eze (king) which is 1,2 it forms the name Adaeze which is 2,8,2.
More examples of tone change are in the notes on usage section of this website.
Given how essential tones are, studying them is probably the most important aspect of language study for tonal languages. And no matter how complex the working of tones may appear, there are stable rules to their use – which is why one faulty tone, like a bad note in an orchestra, immediately stands out.