To the one claiming "The History of Chinese (the language) is based on a script of Indo-Sino-Tibetan":
First, Chinese characters are an unique pictographic symbols representing both meaning and syllable different from all other writing forms in the world including Indic and Tibetan scripts both being phonetic symbols only recording syllables.
Hanzi had no one to copy.
Second, the highly mature Chinese script Oracle Bone Inscriptions emerged around 1300B.C., and its embryonic stage was believed to date back 8000 years ago.
In comparison, the earliest Indic script emerged around 300B.C (over 1000 years later than Chinese character), Tibetan script was created around 700A.D. inspired by indic script Sanskrit.
If you insist on the relations among the three, the only thing you can say is the other two derived from Chinese characters!
Another clarification:
Hanzi was not created in your claimed Zhou Dynasty, it merged much earlier in Shang Dynasty (1700B.C.-1100B.C) (prior to Zhou).
The land of Shang Dynasty and Zhou Dynasty both spanned mostly the central plain reaching northward Liaoning, southward Yangze River and westward Shanxi and Gansu (no Tibet,let alone India).
and Shang people were Han Chinese.
Besides, the unearthed locations of embryonic Chinese characters were all in eastern part of China like: heart of the Central Plain and the middle and lower reaches of Yangze River traditionally Han Chinese populated far far away from Tibet especially India parted by Himalaya Mountain.
Chinese character's invention never ever involved Indian and Tibetan.
Oh, "China (PRC) today do not hold the right to the Old Chinese ",
Why? Today's Chinese are descendants of ancient Chinese, all ancient Chinese cultural achievements are a legacy for today's Chinese people, otherwise who else would be entitled to them?
Regarding the difference between ancient and modern Chinese characters,
The style of Chinese characters had been fixed on the whole in West Han Dynasty (202B.C.-9A.D.) and passed down to modern China generation by generation since, the later gradual minor changes were most about fonts and aestheticism .
Also at that time, the simplified characters (more than 80% of which are being used by mainland Chinese nowadays) were gradually born and have been co-existing with the formal one (we call traditional characters today, being used by present day Taiwanese and HKers).
See, all ancient characters had been consistently handed down, the simplified one is in Mainland China now, the formal one also known as the traditional one is in Taiwan and Hk also in Japan that is Kanji( brought into use in Japan around 500A.D.).