I know. Apart from the so-called Big Clubs (or very big clubs) - there used to be a lot more big clubs in the sense of equal chances of success at the top level - which I suppose are the Manchesters (and City really only since the ME owners took them over), Arsenal, Chelsea (again really only since the Russian Mr A took them over), Spurs (in theory - they are yet to win much of importance in the present era) and Liverpool (can they recapture glories of the past?).
Almost anyone else could find themselves in a relegation battle in any season.
When I began to follow football in 1955 - I was only a lad in short trousers

and my first game was in January 1955 involving Second Division Bristol Rovers 2 First Division Portsmouth 1, FA CUP 3rd Round, Eastville Stadium before 36,000 spectators when the FA Cup really meant something - the likes of Bournemouth, Southampton (I remember watching Soton v Bournemouth in a Div 3 South match in 1956), Crystal Palace, Swansea Town (as they were then), Brighton, Coventry (featured in my first league match v Bristol City who won 2-0 at Ashton Gate in Div 3 South in February 1955 when Coventry had England Under 23, later full international, Reg Matthews in goal) and Watford were 'traditional' third tier (no fourth tier then)/occasional second tier clubs.
Some of the bigger clubs who were regulars in the First Division in that era were Blackpool (with the great Stanley), Bolton, Preston, Wolves (those wonderful televised floodlit* friendlies against the likes of Moscow Spartak and Honved in the days before the European Cup and before the Football League would allow its matches to be played under lights), Everton, Villa, WBA, Sunderland (once called the 'Bank of England' club), the Sheffields (the yo-yo clubs of the 50s between the First and Second divisions) and, go on, Birmingham City with dear old Gil Merrick the first England keeper I was aware of, as well as todays so-called giants.
The first FA Cup Final I saw live on the telly was the 1954 match WBA 3 Preston 2. In those days FA Cup Finals and England internationals on Wednesday afternoons were about the only live football shown on the telly although in 1954 the World Cup Finals were in Switzerland and many of the matches were shown live, albeit the transmission would frequently break down. My folks had just got themselves a small 12 inch telly and I was able to watch some of the games, those in the evenings.
* the pictures were very grainy and in monochrome of course.