Although there are many more, and many of those considered here will have a variety of sub-groups within them according to linguists, I wish to consider here only 4 major language families that have dominated India, the Middle East and Europe. These are the Agglutinative languages, including Saami, Finnish, Estonian. Hungarian and Turkic languages; the Indo-European languages including English, German, Greek, Italian French as well as Persian and Sanskrit; the Semitic languages, including Aramaic, Arabic, and Hebrew; Dravidian languages, including Kanada, Telugu, Tamil and Malayalam.
I do not speak languages from the other families and only smatterings of some Indo-european languages, but have studied Sanskrit and, in a more informal way, Greek, Swedish, Czech and Welsh. I am not in any way fluent with these last languages but have sufficient knowledge to be able to recognise terms and suggest related origins. I may look at alphabets elsewhere. I have also studied Finnish but made no great progress there.
Any linguistic representation in letters is subject to the accuracy of the listener adopting letters to represent sound values. Welsh was put into letters much later than English and the Welshman has a far more acute ear for sounds than the Englishman or woman in general. In language it is sound that is first. Letters come later. Or as one scholar once told me ‘in linguistics vowels count for nothing and consonants even less’. Or perhaps I have got that back to front.
An example here of a sound which is not present in English unless it be in the swallowed sound of the ‘r’ that is so distinctive, compared with the rolled ‘r’ of the Scots or Welsh speakers. In Welsh there is a letter ‘rh’ in which the ‘h’ is sounded as an aspirate at the same time or following the ‘r’. It is found in names such as Rhiannon and elsewhere. This letter is also found in Greek where it is present in Rhodos, and has come into English as Rhododendron, without the characteristic sound associated with it. However I believe it to be the same letter which in Czech language is written as ‘r’ with an inverted circumflex above it. This is called a haček (pronounced ha-check). It is found in the names Jiři and Dvořak. The sound is of rolling the ‘r’ and at the same time pronouncing a ‘zh’ sound behind it.
This letter itself may be related to the semi-vowel ‘ŗ’ in Sanskrit (pronounced ‘ri’) which finds its place in such names as Kŗsna.
The Welsh also distinguish between ‘dd’ ‘-th’ and ‘th’ ‘th-‘. English makes do with one letter combination, ‘th’, for both ‘with’ and ‘thing’.